Disease manifestations in COVID-19 range from mild to severe illness associated with a dysregulated innate immune response. Alterations in function and regeneration of dendritic cells (DCs) and monocytes may contribute to immunopathology and influence adaptive immune responses in COVID-19 patients. We analyzed circulating DC and monocyte subsets in 65 hospitalized COVID-19 patients with mild/moderate or severe disease from acute illness to recovery and in healthy controls. Persisting reduction of all DC subpopulations was accompanied by an expansion of proliferating Lineage−HLADR+ cells lacking DC markers. Increased frequency of CD163+ CD14+ cells within the recently discovered DC3 subpopulation in patients with more severe disease was associated with systemic inflammation, activated T follicular helper cells, and antibody-secreting cells. Persistent downregulation of CD86 and upregulation of programmed death-ligand 1 (PD-L1) in conventional DCs (cDC2 and DC3) and classical monocytes associated with a reduced capacity to stimulate naïve CD4+ T cells correlated with disease severity. Long-lasting depletion and functional impairment of DCs and monocytes may have consequences for susceptibility to secondary infections and therapy of COVID-19 patients.

Measurable residual disease (MRD) quantified by multiparameter flow cytometry (MFC) is a strong and independent prognostic factor in acute myeloid leukemia (AML). However, several technical factors may affect the final read-out of the assay. Experts from the MRD Working Party of the European LeukemiaNet evaluated which aspects are crucial for accurate MFC-MRD measurement. Here, we report on the agreement, obtained via a combination of a cross-sectional questionnaire, live discussions, and a Delphi poll. The recommendations consist of several key issues from bone marrow sampling to final laboratory reporting to ensure quality and reproducibility of results. Furthermore, the experiences were tested by comparing two 8-color MRD panels in multiple laboratories. The results presented here underscore the feasibility and the utility of a harmonized theoretical and practical MFC-MRD assessment and are a next step toward further harmonization.

Background: AMG 673 is a novel half-life extended (HLE) BiTE® (bispecific T-cell engager) construct that binds both CD33 and CD3 and is genetically fused to the N-terminus of a single-chain IgG Fc region, thereby potentially increasing the half-life of the molecule. AMG 673 redirects T cells toward CD33+ cells, with the induced proximity leading to T-cell‒mediated cytotoxicity against acute myeloid leukemia (AML) blasts. Anti-AML activity of other CD33/CD3 bispecific T-cell engager molecules has been previously reported (Blood, 2018, 132, 25; Blood, 2018, 132, 1455). The objectives of this ongoing study are to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary efficacy of AMG 673 in adult patients aged ≥18 years with relapsed/refractory (R/R) AML. Methods: This is an ongoing first-in-human, open-label, phase 1, sequential dose escalation study (NCT03224819). AMG 673 was administered as two, short, and intermittent intravenous (IV) infusions during a 14-day cycle in adult patients with R/R AML. Patients received treatment cycles of AMG 673 until disease progression or unacceptable toxicities. T-cell activation, cytokine, and AMG 673 levels in patients' blood were evaluated by validated assays. Results were summarized descriptively by the dosing cohorts and potential associations between PK, PD, safety, and preliminary efficacy were evaluated. Results: As of June 14, 2019, 30 patients had enrolled in 10 cohorts and were treated with AMG 673 (dose range, 0.05-72 μg IV per dose). The median age was 67.5 (range: 25.0-84.0) years; 20/30 (67%) patients had received ≥4 prior anti-AML treatments, baseline myelosuppression at study entry was common (grade ≥3 neutropenia 21/30 [70%], thrombocytopenia 25/30 [83%], leukopenia 14/30 [47%]), and 7/30 (23%) patients had undergone hematopoietic stem cell transplant (HSCT) before enrolling in the study. Patients received a median of 1.5 (range: 1.0-6.0) cycles of AMG 673; 27/30 (90%) patients discontinued treatment due to disease progression (n=21), patient request (n=2), protocol-specified criteria (n=2), or adverse events (AEs; n=2). A total of 3 patients were still receiving AMG 673 at the time of data analysis. The most common treatment-related AE was cytokine release syndrome (CRS) reported in 15/30 (50%) patients (grade 1, n=6; grade 2, n=5; grade 3, n=4; no grade 4 CRS). Treatment-related serious AEs were reported in 11/30 (37%) patients, and 15/30 (50%) patients experienced treatment-related AEs of grade ≥3, with the most common being abnormal hepatic enzymes (n=5, 17%), CRS (n=4, 13%), leukopenia (n=4, 13%), thrombocytopenia (n=2, 7%), and febrile neutropenia (n=2, 7%). Two deaths, unrelated to AMG 673, were reported on days 19 and 28 after the last dose. Assessment of bone marrow in treated patients showed a decrease in blasts in 12/27 (44%) evaluable patients, of which 6 experienced ≥50% reduction in blasts compared with baseline (Figure 1). One patient achieved complete remission with incomplete hematologic recovery (CRi) with 85% reduction in bone marrow blasts at a dose of 36 µg. Dose-related increases in Cmax and AUC were observed following AMG 673 infusions. Preliminary half-life estimates for AMG 673 were longer than those observed for canonical CD33-specific BiTE® molecule with short half-lives. Upregulation of T-cell activation markers CD25 and CD69 on T-cell subsets and cytokine release post-infusion were observed at higher doses. Preliminary associations between AMG 673 exposures, T-cell activation, safety, and clinical response have been evaluated. Conclusions: Preliminary data of AMG 673 dosed up to 72 µg provide early evidence of the molecule's acceptable safety profile, drug tolerability, and anti-leukemic activity. An association was observed between PK/PD relationships that were consistent with the biological activity of AMG 673. These preliminary results support further dose escalation of the AMG 673 HLE BiTE® molecule in patients with R/R AML. Disclosures Subklewe: AMGEN: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Morphosys: Research Funding; Janssen: Consultancy; Celgene: Consultancy, Honoraria; Miltenyi: Research Funding; Oxford Biotherapeutics: Research Funding; Pfizer: Consultancy, Honoraria. Stein:Celgene: Speakers Bureau; Stemline: Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Walter:Amgen: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Seattle Genetics: Research Funding; Boehringer Ingelheim: Consultancy; Boston Biomedical: Consultancy; Covagen: Consultancy; Daiichi Sankyo: Consultancy; Agios: Consultancy; Race Oncology: Consultancy; Jazz Pharmaceuticals: Consultancy; Kite Pharma: Consultancy; Pfizer: Consultancy, Research Funding; New Link Genetics: Consultancy. Wei:Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Honoraria, Research Funding; Janssen: Honoraria; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax, Research Funding, Speakers Bureau. Ritchie:Amgen: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; BMS: Research Funding; Takeda: Research Funding; Beigene: Research Funding; Imago: Research Funding; Novartis: Honoraria; Sanofi: Honoraria. Vachhani:AbbVie: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Agios: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Astellas: Speakers Bureau. Dai:Amgen: Employment, Equity Ownership. Hindoyan:Amgen Inc.: Employment, Other: stock ownership. Agarwal:Amgen: Employment, Equity Ownership; AbbVie: Equity Ownership. Anderson:Amgen Inc.: Employment, Equity Ownership. Khaldoyanidi:Amgen: Employment, Equity Ownership; BMS: Equity Ownership. Ravandi:Macrogenix: Consultancy, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Xencor: Consultancy, Research Funding; Menarini Ricerche: Research Funding; Selvita: Research Funding; Cyclacel LTD: Research Funding.

Background: Current treatment options for R/R AML are highly inadequate. CD33 is expressed in >99% of AML cases. BiTE®s have been effective in R/R Acute Lymphoblastic Leukemia. AMG 330 is a BiTE® that binds CD33 and CD3 on T cells, facilitating T-cell destruction of CD33+ cells. The objectives of this ongoing study are to evaluate the safety, pharmacokinetics, and pharmacodynamics of AMG 330 in R/R AML and to estimate the maximum tolerated dose. Methods: This was a phase 1 dose escalation study evaluating AMG 330 as a continuous IV infusion in patients with R/R AML, with single-patient cohorts for the first 3 doses and subsequently 3-6 patients per cohort (NCT#02520427). Response was per revised IWG criteria with the addition of complete response (CR) with partial hematologic recovery. After completing the first cycle without dose-limiting toxicity (DLT), up to 5 additional cycles could be given for benefit. After the 30 μg/day (d) cohort, risk mitigation measures for cytokine release syndrome (CRS) were put in place, including step-dosing and pretreatment with a single dose of corticosteroids. The modified treatment regimen consisted of an initial run-in dose of 10 μg/d × 4d followed by the target dose. A 2-step regimen was then tested, ie 10 μg/d, 60 μg/d, and then the target dose, for a treatment duration of 14d or 28d, followed by 1-4 weeks off treatment. Results: As of June 14, 2018, 35 patients had enrolled in 12 dose cohorts with a target dose range of 0.5-480 μg/d in this ongoing study. Over half (20/35, 57%) of patients were male and the median age was 58 (range: 18-80) years; 14/35 (40%) have previously received a stem cell transplant. Median AML disease duration at baseline was 1.3 (range: 0.3-9.6) years, median proportion of blasts at baseline was 37% (range: 3%-95%), and the median # of prior treatments was 4 (range: 1-15). Median baseline ANC was 0.2 (range: 0-8.6) × 109/L. Patients received a median of 1 (range: 1-6) cycle with AMG 330; 31/35 (89%) patients discontinued treatment for disease progression (n=24), adverse events (AEs; n=5, 2 treatment-related), and patient request (n=2). One patient completed the maximum of 6 cycles allowed and 3 patients are still receiving study drug. Serious AEs (SAEs) were seen in 23/35 (66%) patients (treatment-related in 15 patients); SAEs seen in >1 patient included CRS (n=11), febrile neutropenia (n=6), pneumonia (n=4), leukopenia (n=3), thrombocytopenia (n=2), and subdural hematoma (n=2); 1 patient died on study due to AML progression (not treatment-related). One patient each in the 10 μg/d and 30 μg/d cohorts (no lead-in) experienced severe CRS; CRS signs and symptoms resolved in 1d with corticosteroids, vasopressors, and IV fluids, and interruption of AMG 330. There were DLTs of grade 2 CRS and grade 4 ventricular fibrillation with a target dose of 480 μg/d; the target dose was then decreased to 240 μg/d. Two patients had a CR at a target dose of 240 μg/d (lead-in of 10 μg/d→60 μg/d); 1 patient each at target doses of 120 μg/d and 240 μg/d had a CRi and 1 patient who received 1.5 μg/d had a morphologic leukemia-free state (MLFS, <5% blasts, no hematologic recovery). One patient with a CR had bone marrow blasts decrease from ~5%-10% (estimated due to patchy disease) to 2.5% by d29 by flow cytometry, with no morphologic evidence of residual AML and normo- to hypercellular marrow and recovery of peripheral blood counts. The second CR patient had blasts decrease from 40% to 3% with recovery of peripheral blood counts by d42 after receiving one cycle of AMG 330. Correlative data will be presented. Conclusions: Preliminary data of AMG 330 dosed up to 480 μg/d provide encouraging early evidence of tolerability and anti-leukemic activity in heavily pre-treated patients with R/R AML. Expected CRS was mitigated through step-up dosing, corticosteroid pretreatment, IV fluids, tocilizumab, and drug interruption if needed; most patients had short periods of CRS which responded well to treatment. A 2-step approach will be used in the future to quickly achieve the target dose and optimize clinical response. Regarding pharmacodynamics, to date, 2 CRs and 2 CRis have been observed at target doses of 120 and 240 μg/d. As nearly all patients were substantially cytopenic at baseline, it is challenging to evaluate the impact of AMG 330 on cytopenias. Of note, both CR patients had a complete recovery of blood counts after one cycle of treatment. These promising data validate the use of the BiTE® platform to target CD33. Figure Figure. Disclosures Ravandi: Sunesis: Honoraria; Bristol-Myers Squibb: Research Funding; Abbvie: Research Funding; Bristol-Myers Squibb: Research Funding; Xencor: Research Funding; Jazz: Honoraria; Orsenix: Honoraria; Xencor: Research Funding; Jazz: Honoraria; Astellas Pharmaceuticals: Consultancy, Honoraria; Seattle Genetics: Research Funding; Macrogenix: Honoraria, Research Funding; Abbvie: Research Funding; Orsenix: Honoraria; Seattle Genetics: Research Funding; Macrogenix: Honoraria, Research Funding; Amgen: Honoraria, Research Funding, Speakers Bureau; Astellas Pharmaceuticals: Consultancy, Honoraria; Sunesis: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau. Stein:Celgene: Speakers Bureau; Amgen: Speakers Bureau. Walter:Amphivena Therapeutics: Consultancy, Equity Ownership, Other: Clinical trial support, Research Funding; Aptevo Therapeutic: Consultancy, Other: Clinical trial support, Research Funding; Covagen AG: Consultancy, Other: Clinical trial support, Research Funding; Seattle Genetics, Inc.: Consultancy, Other: Clinical trial support, Research Funding; Boehringer Ingelheim Pharma GmbH & Co. KG: Consultancy; Pfizer: Consultancy; Amgen Inc.: Other: Clinical trial support, Research Funding; Actinium Pharmaceuticals, Inc.: Other: Clinical trial support, Research Funding. Paschka:Amgen: Other: Travel support; Jazz: Speakers Bureau; Bristol-Meyers Squibb: Other: Travel support, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees; Janssen: Other: Travel support; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Otsuka: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees, Travel support; Astex: Membership on an entity's Board of Directors or advisory committees; Sunesis: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Travel support. Ossenkoppele:Celgene: Honoraria, Research Funding; Roche: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Karyopharm: Consultancy, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Genmab: Research Funding; Johnson & Johnson: Consultancy, Honoraria, Research Funding. Yang:Amgen Inc.: Employment, Equity Ownership. Mehta:Amgen Inc.: Employment, Equity Ownership. Subklewe:Roche: Consultancy, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Gilead: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.

Background: Mutations in the protein tyrosine phosphatase gene PTPN11 (also known as SHP2) are found in approximately 10% of adult patients with acute myeloid leukemia (AML). A recent study reported that mutated PTPN11 associates with inferior response rates and shorter survival among intensively treated AML patients, independently of the ELN prognostic groups (Alfayez et al., Leukemia 2020). Earlier analyses of the genomic landscape of AML did not uncover a similar prognostic relevance of PTPN11 mutations. Therefore, our aim was to clarify the prognostic relevance of mutated PTPN11 variants in AML patients receiving intensive front-line therapy. Patients and Methods: We studied 1116 AML patients enrolled on two subsequent multicenter phase III trials of the German AML Cooperative Group (AML-CG 1999, NCT00266136; and AML-CG 2008, NCT01382147) who were genetically characterized by amplicon-based targeted next-generation sequencing (Herold et al., Leukemia 2020). All patients had received induction chemotherapy containing cytarabine and daunorubicin or mitoxantrone. Results: We identified 146 PTPN11 mutations in 114 of 1116 patients (10%). Mutations clustered in two hotspot regions (5': codons 52-79; n=108 and 3': codons 491-512, n=38) as previously reported. Associations of PTPN11 mutations with baseline clinical and genetic patient characteristics are shown in Figure A. PTPN11 mutations were most frequent in the European LeukemiaNet (ELN) "favorable" genetic risk group, and associated with higher leukocyte counts. Patients with mutated PTPN11more commonly had mutated NPM1, IDH1 and DNMT3A, and less frequently had FLT3-ITD, IDH2 and TP53 mutations, compared to patients with wild-type PTPN11. With regard to treatment outcomes, the rate of complete remission was similar among patients with mutated and wild-type PTPN11 (65% vs. 59%, P=.25). In univariate analyses, PTPN11-mutated patients had significantly longer relapse-free survival (RFS; 5-year estimate, 55% vs 33% for PTPN11-wild type patients; P=.001; Figure B) and tended to have longer overall survival (OS; 5-year estimate, 43% vs 32%; P=.06; Figure C). However, in multivariable models adjusting for age, sex, leukocyte count, AML type (de novo/sAML/tAML) and ELN-2017 genetic risk group, mutated PTPN11 no longer associated with RFS (hazard ratio [HR], 0.89, 95% confidence interval [CI], 0.63 - 1.27; P=0.53) or OS (HR, 1.03; 95% CI, 0.80 - 1.33; P=.79). Moreover, PTPN11 mutations did not significantly associate with RFS or OS within any of the ELN genetic risk groups. Finally, we detected no significant differences in baseline characteristics or outcomes between patients with PTPN11 mutations affecting the 5' hotspot region (n=82), the 3' hotspot region (n=21), or mutations at both hotspots (n=11). Conclusion: In our cohort of newly diagnosed and intensively treated AML patients, mutations in PTPN11 occurred in 10% and associated with prognostically favorable genetic characteristics such as mutated NPM1 and absence of FLT3-ITD and TP53mutations. Consequently, PTPN11 mutations were most commonly found within the ELN-2017 favorable risk category. While patients with PTPN11 mutations had relatively favorable survival outcomes, multivariable models suggest this observation is confounded by the frequent co-occurrence of known favorable genetic markers. Our data are in disagreement with a recently published study on 880 newly diagnosed patients that found an unfavourable prognostic impact of mutated PTPN11, particularly among the 410 patients who received intensive treatment. Possible explanations for these discrepant results include differences in treatment regimens between the two cohorts, as well as the play of chance when studying a relatively rare gene mutation in medium-sized cohorts. In summary, our data do not support a role of PTPN11 mutations as an adverse prognostic biomarker in newly diagnosed, intensively treated adult AML patients. Figure Disclosures Metzeler: Daiichi Sankyo: Honoraria; Otsuka Pharma: Consultancy; Pfizer: Consultancy; Celgene: Consultancy, Honoraria, Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy; Astellas: Honoraria. Subklewe:AMGEN: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Research Funding; Janssen: Consultancy; Morphosys: Research Funding; Seattle Genetics: Research Funding; Roche AG: Consultancy, Research Funding; Gilead Sciences: Consultancy, Honoraria, Research Funding.

No abstract

Antibodies against the spike protein of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) can drive adaptive evolution in immunocompromised patients with chronic infection. Here we longitudinally analyze SARS-CoV-2 sequences in a B cell-depleted, lymphoma patient with chronic, ultimately fatal infection, and identify three mutations in the spike protein that dampen convalescent plasma-mediated neutralization of SARS-CoV-2. Additionally, four mutations emerge in non-spike regions encoding three CD8 T cell epitopes, including one nucleoprotein epitope affected by two mutations. Recognition of each mutant peptide by CD8 T cells from convalescent donors is reduced compared to its ancestral peptide, with additive effects resulting from double mutations. Querying public SARS-CoV-2 sequences shows that these mutations have independently emerged as homoplasies in circulating lineages. Our data thus suggest that potential impacts of CD8 T cells on SARS-CoV-2 mutations, at least in those with humoral immunodeficiency, warrant further investigation to inform on vaccine design.

No abstract